The present invention concerns the use of light pulses that are transmitted, reflected from external objects, and received by a detector to locate the objects in the field of view of the transmitter. By pulsing a laser emitter and receiving the reflection, the time required for the pulse of light to return to the detector can be measured, thereby allowing a calculation of the distance between the emitter and the object from which the pulse was reflected.
When multiple pulses are emitted in rapid succession, and the direction of those emissions is varied, each distance measurement can be considered a pixel, and a collection of pixels emitted and captured in rapid succession (called a “point cloud”) can be rendered as an image or analyzed for other reasons such as detecting obstacles. Viewers that render these point clouds can manipulate the view to give the appearance of a 3-D image.
In co-pending application Ser. No. 11/777,802, the applicant described a variety of systems for use in creating such point cloud images using Laser Imaging Detection and Ranging (LiDAR). In one version, the LiDAR system was used for terrain mapping and obstacle detection, and incorporated as a sensor for an autonomous vehicle. An exemplary LiDAR system included eight assemblies of eight lasers each as shown in FIG. 1, or two assemblies of 32 lasers each forming a 64-element LiDAR system as shown in FIG. 2. Yet other numbers of lasers or detectors are possible, and in general the LiDAR was employed in an assembly configured to rotate at a high rate of speed in order to capture a high number of reflected pulses in a full circle around the LiDAR sensor.
The preferred examples of the present invention described further below build on the inventor's prior work as described above, incorporating several improvements to reduce the overall size and weight of the sensor, provide better balance, reduce crosstalk and parallax, and provide other advantages.